Fecal leukocytes are a type of cell found in stool samples, representing a component of the body’s immune system. Their presence in stool can provide insights into the digestive system’s health. Observing them helps healthcare providers gather information about gut health.
Understanding Fecal Leukocytes
Fecal leukocytes are white blood cells, also known as leukocytes, that have migrated from the bloodstream into the intestines and are subsequently passed in stool. Normally, these cells are not present in feces. Their appearance suggests an ongoing inflammatory process or infection within the digestive tract.
The primary types of white blood cells commonly observed in stool samples are neutrophils. Neutrophils are a type of phagocytic immune cell, serving as a first line of defense against infection or tissue damage. They are typically among the first leukocytes to be recruited to a site of inflammation. These cells play a role in protecting the integrity of the intestinal epithelial barrier and containing pathogens.
Purpose of Fecal Leukocyte Testing
A healthcare provider may order a fecal leukocyte test to determine if symptoms such as diarrhea are linked to inflammation or infection in the digestive system. Diarrhea caused by inflammation is often severe, lasting more than a few days, and may include symptoms like abdominal pain, fever, or blood or mucus in the stool.
This test serves as a screening tool, suggesting whether an inflammatory process is occurring, but it does not provide a definitive diagnosis on its own. The information from a fecal leukocyte test guides further diagnostic steps to identify the specific underlying condition.
What Test Results Indicate
Positive Results
The presence of fecal leukocytes in a stool sample, a positive result, signifies active inflammation in the digestive tract. The number of leukocytes found can be reported semi-quantitatively, such as “few,” “moderate,” or “many.” A higher count suggests a greater likelihood of an invasive pathogen.
Negative Results
A negative test result means that no white blood cells were found in the stool sample. This suggests that inflammation may not be the cause of the illness. However, a negative result does not completely rule out all conditions that cause inflammation, as some individuals with inflammatory conditions may not show fecal leukocytes. Certain medications, such as corticosteroids, can also suppress the immune response, leading to low fecal leukocyte levels even in the presence of an issue.
Specific Conditions
The presence of fecal leukocytes is commonly associated with certain bacterial infections. These include Salmonella, Shigella, and Campylobacter, which are known to cause tissue invasion or produce toxins that damage tissue. Clostridium difficile (C. diff) infection, often occurring after antibiotic use, can also lead to the presence of fecal leukocytes. Certain types of E. coli can also cause an inflammatory response with fecal leukocytes.
Inflammatory Bowel Disease (IBD), which encompasses conditions like Crohn’s disease and ulcerative colitis, is another common cause of fecal leukocytes. In ulcerative colitis, neutrophil accumulation in the stool often correlates with active disease and disease severity. While less common, certain parasitic infections like amebiasis can also lead to the presence of fecal leukocytes, though typically with fewer leukocytes and more red blood cells compared to bacterial infections.
Next Steps
A positive fecal leukocyte test result prompts further diagnostic tests to pinpoint the exact cause of the inflammation. These additional tests may include stool cultures to identify specific bacterial pathogens, or tests for other inflammatory markers such as fecal lactoferrin or calprotectin, which are proteins released by white blood cells during inflammation. If symptoms are severe or persistent, a colonoscopy might be recommended to directly visualize the intestinal lining and obtain biopsies.